Credit-rating companies failed to follow their own standards, were late to downgrade deals and delayed disclosure of methodology changes this year, according to the U.S. Securities and Exchange Commission.

The watchdog didn’t name specific companies, separating them as either “larger firms,” including McGraw-Hill Co.’s Standard & Poor’s, Moody’s Corp.’s Moody’s Investors Service and Fitch Ratings, and six others, such as Kroll Bond Rating Agency Inc. and DBRS Inc. as “smaller firms.”

The three larger firms as well as two smaller companies failed to follow their own methodologies in determining ratings, the Office of Credit Ratings said today in its annual report on Nationally Recognized Statistical Rating Organizations or NRSROs, which is required by the Dodd-Frank financial reform act. The SEC found that one of the NRSROs changed a key financial ratio for rating asset-backed securities and is concerned the company may have been “influenced by market share,” in grading the securities.

After inflated credit ratings for risky mortgage bonds were blamed for helping cause the worst financial crisis since the Great Depression, policy makers have been searching for a way to ensure the grades are accurate. Dodd-Frank, which became law in 2010, instructed regulators to stop relying on ratings and increase oversight of the companies that issue them.

“One of the larger NRSROs delayed downgrading a number of structured finance transactions in order, the Staff believes, to give the issuers or other relevant parties the opportunity to avoid downgrades by restructuring their transactions and in anticipation of regulatory action,” the SEC wrote in the report.

In 1936, the Office of the Comptroller of the Currency banned banks from holding bonds that were below investment grade. The SEC began using ratings in its rules in 1975, specifying that the only companies whose grades could be used were S&P, Moody’s and Fitch.